(1) Field of the Invention
This invention relates to aircraft, and more particularly to heating systems for rotary wing aircraft.
(2) Description of the Related Art
Bleed air is for a variety of purposes in rotary-wing aircraft. An exemplary aircraft is the UH-60/S70 BLACKHAWK by Sikorsky Aircraft Corporation, Stratford, Conn. The interior of this aircraft has a forward cockpit and a passenger cabin or compartment aft of the cockpit. A pair of port and starboard main turbine engines are located above the cabin below the main rotor. An auxiliary power unit (APU) having its own turbine is located high in the transition area behind the cabin. The compressors of the main engines and APU all produce bleed air which bypasses combustion. In a standard configuration, a bleed conduit system can direct air from the three compressors for a variety of purposes. Air from the APU may be used to start the engines. Air from one engine may be used to start the other in a so-called cross-bleed start. Conduits may extend over the cabin and into the cockpit to heat the cockpit or defrost cockpit windows. Bleed air may be utilized for de-icing of the engines. Bleed air may be utilized to power air conditioners. Additional conduits may run aft into a transition region aft of the cabin and ahead of the tail to an external port on the aircraft fuselage. This port may allow the aircraft to provide or receive compressed air. In one example of a so-called “buddy start”, the ports of a donor and recipient aircraft are coupled via a hose. Initially the APU and/or main engines of the donor aircraft are running while those of the recipient are not. Bleed air passes through the hose from the donor to recipient aircraft to start the main engines of the recipient aircraft. This may be appropriate, for example, when the recipient aircraft has a broken APU or simply does not have an APU.